Optical fibers such as double cladding fibers and triple cladding fibers, in which light can be confined to a cladding, are in wide use. According to such an optical fiber, unnecessary light that propagates in a cladding (hereinafter referred to as “cladding light”) may cause heating in a jacket which covers an outer surface of the cladding. Under the circumstances, in such an optical fiber, it is necessary to cause the cladding light to leak from the cladding through a jacket-removed section in which the jacket has been removed.
Patent Literature 1 discloses an optical device including (i) an optical fiber in which a jacket-removed section is provided (jacket is referred to as a “pre-coating” in Patent Literature 1) and (ii) a resin member in which the jacket-removed section is embedded. According to the optical device disclosed in Patent Literature 1, a refractive index of the resin member is set to be higher than that of a cladding so that cladding light will leak from the cladding into the resin member through the jacket-removed section.